gopatterns/pkg/pattern/point/point.go

// Package point contains different types of points for drawing patterns.
// There are points that define an absolute position or a relative position.
// Relative can be a specific distance one point or between two other points.
package point

import (
	"git.wtrh.nl/wouter/gopatterns/pkg/position"
	"git.wtrh.nl/wouter/gopatterns/pkg/vector"
	"github.com/tdewolff/canvas"
)

// ID defines a point id.
type ID string

// Point defines the interface for different types of points.
type Point interface {
	// ID returns the point ID.
	ID() ID

	// Position calculates and returns the absolute [position.Position].
	Position() position.Position

	// Vector calculates and returns the absolute [vector.Vector].
	Vector() vector.Vector

	// Matrix calculates and returns the [canvas.Matrix] of a point.
	Matrix() canvas.Matrix

	// Name returns the name of a point.
	Name() string

	// SetDraw indicates that the point should be drawn.
	SetDraw()

	// Draw returns if the point should be drawn.
	Draw() bool

	// Hide returns if the point must remain hidden.
	Hide() bool

	// SetHide indicates that the must be hidden.
	SetHide()
}

// Draw draws a specific Point to the provided [canvas.Canvas].
// The point is only drawn when the point states that it should be drawn and not must be hidden.
func Draw(c *canvas.Canvas, point Point, face *canvas.FontFace) {
	if !point.Draw() || point.Hide() {
		return
	}

	path := canvas.Circle(1.0)
	m := point.Matrix()
	style := canvas.Style{Fill: canvas.Paint{Color: canvas.Black}}
	c.RenderPath(path, style, m)

	text := canvas.NewTextLine(face, point.Name(), canvas.Bottom)
	c.RenderText(text, m.Translate(2, -4))
}